This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primary objective of the TODAY trial is to compare the efficacy of the three treatment arms on time to treatment failure based on glycemic control in subjects from 10-17 years of age with type 2 diabetes mellitus. The secondary aims are to: compare and evaluate the safety of the three treatment arms; compare the effects of the three treatments on the pathophysiology of T2DM with regards to b-cell function and insulin resistance, body composition, nutrition, physical activity, and aerobic fitness, cardiovascular risk factors, microvascular complications, quality-of-life, and psychological outcomes; evaluate the influence of individual and family behaviors on treatment response;and compare the relative cost-effectiveness of the three treatment arms. The three treatment regimens are: : metformin alone versus metformin plus intensive lifestyle intervention called the TODAY Lifestyle Program;metformin alone versus metformin plus rosiglitazone, and;metformin plus TLP versus metformin plus rosiglitazone. The study recruits subjects over a three-year period and follows them for a minimum of two years. Subjects are randomized within two years of the diagnosis of T2DM. The primary outcome of treatment failure is defined in terms of HbA1c 8.0% over a 6-month period;or inability to wean off temporary insulin.